1. Field of the Invention
The present invention relates generally to inductive magnetic write transducer heads employed in magnetic data recording and retrieval. More particularly, the present invention relates to narrow write track width inductive magnetic write transducer heads employed in magnetic data recording and retrieval.
2. Description of the Related Art
The recent and continuing advances in computer and information technology have been made possible not only by the correlating advances in the functionality, reliability and speed of semiconductor integrated circuits, but also by the correlating advances in the storage density of direct access storage devices (DASDs) employed in digitally encoded magnetic data storage and retrieval.
Storage density of direct access storage devices (DASDs) is typically measured as areal storage density of a magnetic data storage medium formed upon a rotating magnetic data storage disk within a direct access storage device (DASD) magnetic data storage enclosure. The areal storage density of the magnetic data storage medium is typically defined largely by the track width, the track spacing and the linear magnetic domain density within the magnetic data storage medium. The track width, the track spacing and the linear magnetic domain density of the magnetic data storage medium are in turn determined by several principal factors, including but not limited to: (1) the magnetic read-write characteristics of a magnetic read-write head employed in reading and writing digitally encoded magnetic data from and into the magnetic data storage medium; (2) the magnetic domain characteristics of the magnetic data storage medium which is formed upon the rotating magnetic data storage disk; and (3) the separation distance of the magnetic read-write head from the magnetic data storage medium formed upon the rotating magnetic data storage disk.
With regard in particular to a track width within a magnetic data storage medium, the track width within the magnetic data storage medium is typically in turn largely defined by a pole tip width of an inductive magnetic write transducer pole tip employed within an inductive magnetic write transducer head which is employed in writing digitally encoded magnetic data into the magnetic data storage medium. Thus, although it is therefore desirable to employ within digitally encoded magnetic data storage and retrieval inductive magnetic write transducer heads having formed therein increasingly narrower inductive magnetic write transducer pole tips within inductive magnetic write transducer pole layers, fabricating inductive magnetic write transducer heads having formed therein increasingly narrower inductive magnetic write transducer pole tips within inductive magnetic write transducer pole layers is not entirely without problems within digitally encoded magnetic data storage and retrieval.
In particular, it is common in the art of inductive magnetic write transducer head fabrication to form inductive magnetic write transducer pole tips through conventional photoresist masking or photoresist frame plating methods which form inductive magnetic write transducer pole tips within inductive magnetic write transducer pole layers formed over irregular surfaces within inductive magnetic write transducer head fabrications. Such irregular surfaces typically include, but are not limited to, surfaces having formed thereupon or thereover magnetic inductor coil layers and associated magnetic inductor coil insulator layers. Due to the topographic variations within the irregular surfaces, there is typically required within the conventional photoresist masking or photoresist frame plating methods sufficiently thick photoresist layers such that optimally fine linewidth features, such as but not limited to optimally narrow linewidth inductive magnetic write transducer pole tips within inductive magnetic write transducer pole layers, are not readily fabricated through the conventional photoresist masking and photoresist frame plating methods. As is understood by a person skilled in the art, optimally fine linewidth features are precluded due to a correlation between: (a) minimal achievable patterned photoresist layer linewidth; and (b) depth of focus limitations, when forming a patterned photoresist layer from a particularly thick blanket photoresist layer. It is thus desirable within the art of inductive magnetic write transducer head fabrication to provide photolithographic methods through which inductive magnetic write transducer pole tips within inductive magnetic write transducer pole layers may be fabricated over irregular surfaces while employing comparatively thin photoresist layers which provide inductive magnetic write transducer pole tips with optimally narrow write track width. It is towards that goal that the present invention is generally directed.
Various novel inductive magnetic transducer heads, and methods of fabrication of those various novel inductive magnetic transducer heads, have been disclosed within the art of inductive magnetic transducer head fabrication.
For example, Ju et al., in U.S. Pat. No. 5,285,340, discloses for use within magnetic data storage and retrieval: (1) a thin film inductive magnetic transducer head with conformable pole tips; and (2) a method for forming the thin film inductive magnetic transducer head with the conformable pole tips. The method employs a single photolithographic process step to provide within the thin film inductive magnetic transducer head a pole tip structure comprising a first pole tip layer formed co-extensively with both a gap forming layer and a second pole tip layer, thus providing a thin film magnetic transducer head with pole tips which are precisely aligned and of a width and of a thickness which are precisely controlled.
In addition, Krounbi et al., in U.S. Pat. No. 5,438,747, discloses a method for fabricating a thin film merged inductive write-magnetoresistive (MR) read magnetic read-write transducer head with aligned pole tips. The method employs an upper magnetic pole tip within an upper magnetic pole layer as an etch mask layer when etching through an ion beam etching method a corresponding lower magnetic pole tip within a lower magnetic pole layer which simultaneously serves as a magnetoresistive (MR) sensor layer shield layer within the thin film merged inductive write-magnetoresistive (MR) read magnetic read-write transducer head. In addition, the ion beam etch method employs an ion beam at an oblique angle with respect to the upper magnetic pole tip within the upper magnetic pole layer to form while employing the upper magnetic pole tip as the etch mask layer the lower magnetic pole tip which is substantially vertically aligned with the upper magnetic pole tip.
Finally, Cole et al., in U.S. Pat. No. 5,452,164, discloses a thin film inductive magnetic write transducer head which employs: (1) a narrow pole tip structure at an air bearing surface (ABS) of the thin film inductive magnetic write transducer head; and (2) a well defined zero throat level at the side opposite the air bearing surface (ABS) side of the narrow pole tip structure. The method employs a photolithographic patterning of an upper magnetic pole tip layer, a gap filling dielectric layer and lower magnetic pole tip within a lower magnetic pole layer prior to forming contacting the upper magnetic pole tip layer an upper magnetic pole layer. The invention as disclosed by Cole et al. is generally directed towards a problem analogous to the problem addressed within the present invention, but the present invention addresses the problem through a patentably distinct method.
The teachings of the foregoing three references are incorporated herein fully by reference.
Desirable within the art of inductive magnetic write transducer head fabrication are photolithographic methods through which inductive magnetic pole tips within inductive magnetic pole layers may be fabricated over irregular surfaces while employing comparatively thin photoresist layers which provide inductive magnetic pole tips with optimally narrow write track width. Particularly desirable within the art of inductive magnetic write transducer head fabrication are methods which realize the foregoing objects while providing manufacturing processes with enhanced manufacturing process control. It is towards the foregoing objects that the present invention is both generally and more specifically directed.